1. Field of the Invention
The present invention relates to a resist composition suited to the formation of a fine, highly-detailed resist pattern, and in particular, to a resist composition using a molecular resist in which the occurrence of nanoedge roughness can be suppressed, and to a method of forming a resist pattern, a semiconductor device, and a method of manufacturing thereof using the resist composition.
2. Description of the Related Art
Conventionally, polymers are generally used as resist compositions for forming resist patterns, from the standpoint that a coated film can be easily obtained at the time of coating by using the resist composition as a coating solution and by using spin coating or the like, and from the standpoint that, due to the exposure thereafter, it is easy for a reaction such as making insoluble or making easily soluble or the like to occur at the developing liquid, or the like. Specifically, examples of the polymer include novolak resin, polyacrylic acid, polyvinyl phenol, polyvinyl pyrrolidone, polyvinyl alcohol, styrene-maleic acid copolymer, melamine resin, and the like.
However, in resist compositions using these polymers, the unit molecules which dissolve in a developing liquid are giant polymer molecules. Therefore, roughness on the order of several tens of nm (hereinafter called “nanoedge roughness” upon occasion) arises at the pattern edges at the time of resolving. As patterns have become more and more fine in recent years, the occurrence of nanoedge roughness has become a great problem.
Thus, in order to suppress the occurrence of nanoedge roughness, research on resist compositions which use monomer molecules instead of polymers which are giant molecules has advanced. Such a resist composition is called a molecular resist, and research on these molecular resists has started in recent years. For example, resist compositions using water-soluble molecules of a calixarene or polyphenyl skeletons, or the like are used as the molecular resist.
However, these molecular resists are a special molecular configuration and are expensive (one gram costs from several thousand yen to several ten-thousand yen), and as compared with polymers, the crystallinity thereof is high, and therefore, the film forming ability thereof is poor. When they are used as a coating liquid, only organic solvents can be used as the solvent, an exclusive-use developing liquid is needed for development, and an exclusive-use removing liquid is needed in the removing of the resist film. Therefore, the problems arise that the costs and the burden on the environment increase.
As a result of studies, the present inventors have found that the aforementioned various problems can be improved by using tannins and derivatives thereof as molecular resists.
As examples of using tannins, there is known, for example, adding and using crosslinking agents or polymerization initiators as examples of organic matter (see Japanese Patent Application Laid-Open (JP-A) Nos. 2002-47375 and 2002-53699). In this case, inorganic fibers are kneaded-in and layered, and the tannins are used in order to fabricate a so-called prepreg for a printed wiring board and not used as a resist to be used for patterning. Further, although the aforementioned JP-A Nos. 2002-47375 and 2002-53699 mention lignin (a component of wood), there is no disclosure whatsoever of how to use tannins.
Further, it has been known that tannins can be used as components of photosensitive compositions (refer to Japanese Patent (JP-B) No. 3275367 and JP-A Nos. 7-128843, 7-128853, 7-209858, and 10-3165). However, in these cases, the tannins are structural units of polymers, and the tannins are used after being copolymerized and made into polymers. Therefore, there is the problem that they cannot aim to reduce nanoedge roughness, reduce costs, and reduce the burden on the environment.
Accordingly, the current situation is that there has not yet been provided a resist composition which can easily and efficiently and at a low cost form a fine, highly-detailed resist pattern at which nanoedge roughness can be suppressed, nor related techniques utilizing such a resist composition.
An object of the present invention is to provide a resist composition which can easily and efficiently and at low cost form a fine, highly-detailed resist pattern at which the occurrence of nanoedge roughness can be suppressed, and further, whose burden on the environment is small; and a method of forming a resist pattern which, by using the resist composition, can easily and efficiently and at a low cost form a fine, highly-detailed resist pattern without nanoedge roughness which can cause problems; and a method of manufacturing a semiconductor device which, by using the resist composition, can form a fine, highly-detailed resist pattern without nanoedge roughness which can cause problems, the method enabling efficient mass production of a high-performance semiconductor device having a fine wiring pattern formed by using the resist pattern; and a high-performance semiconductor device having a fine wiring pattern and manufactured by the method of manufacturing a semiconductor device.
As the result of diligent studies, the present inventors have obtained the following findings. Namely, the present inventors have found that, when using a molecular resist, and in particular, at least one of a tannin and derivatives thereof, as a resist composition for forming a resist pattern, tannins and derivatives thereof can be obtained inexpensively (100 grams for about 2000 yen), and the film forming ability thereof is good despite the fact that they are low molecules, and they suppress the occurrence of nanoedge roughness such that a fine resist pattern can be obtained. Further, the present inventors have found that, because tannins are water soluble, water can be used as a coating solvent and a developing liquid, an alkali aqueous solution can be used at the time of resist removing, costs and the burden on the environment can be reduced, and in particular, when the tannin is a natural product, the burden on the environment can be reduced even more, and the present inventors thereby completed the present invention.